> From: Baolu Lu <baolu...@linux.intel.com>
> Sent: Tuesday, June 28, 2022 1:41 PM
> >
> >>   struct iommu_domain {
> >>    unsigned type;
> >>    const struct iommu_domain_ops *ops;
> >>    unsigned long pgsize_bitmap;    /* Bitmap of page sizes in use */
> >> -  iommu_fault_handler_t handler;
> >> -  void *handler_token;
> >>    struct iommu_domain_geometry geometry;
> >>    struct iommu_dma_cookie *iova_cookie;
> >> +  union {
> >> +          struct {        /* IOMMU_DOMAIN_DMA */
> >> +                  iommu_fault_handler_t handler;
> >> +                  void *handler_token;
> >> +          };
> >
> > why is it DMA domain specific? What about unmanaged
> > domain? Unrecoverable fault can happen on any type
> > including SVA. Hence I think above should be domain type
> > agnostic.
> 
> The report_iommu_fault() should be replaced by the new
> iommu_report_device_fault(). Jean has already started this work.
> 
> https://lore.kernel.org/linux-iommu/Yo4Nw9QyllT1RZbd@myrica/
> 
> Currently this is only for DMA domains, hence Robin suggested to make it
> exclude with the SVA domain things.
> 
> https://lore.kernel.org/linux-iommu/f3170016-4d7f-e78e-db48-
> 68305f683...@arm.com/

Then it's worthy a comment that those two fields are for
some legacy fault reporting stuff and DMA type only.

> >
> >> +
> >> +  mutex_lock(&group->mutex);
> >> +  curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, domain,
> >> GFP_KERNEL);
> >> +  if (curr)
> >> +          goto out_unlock;
> >
> > Need check xa_is_err(old).
> 
> Either
> 
> (1) old entry is a valid pointer, or

return -EBUSY in this case

> (2) xa_is_err(curr)

return xa_err(cur)

> 
> are failure cases. Hence, "curr == NULL" is the only check we need. Did
> I miss anything?
> 

But now you always return -EBUSY for all kinds of xa errors.
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